Hydrotesting and Mothballing Composition and Method of using Combination Products for Multifunctional Water Treatment

ABSTRACT

This invention relates to a composition, comprising
         a) at least one quaternary ammonium compound of the formula (I)       

     
       
         
         
             
             
         
       
         
         
           
             
               
                 wherein 
                 R is a C 5  to C 21  aliphatic hydrocarbon group, 
                 X is an anionic counter ion, and 
                 R a , R b  are selected from the group consisting of hydrogen, methyl, ethyl, allyl, propyl, butyl, phenyl or benzyl residues, 
               
             
             b) ammonium bisulfite or sodium bisulfite, 
             c) glutaraldehyde or THPS, and 
             d) at least one organic dye.

FIELD OF INVENTION

This invention involves compositions for hydrotesting and/or mothballingof oilfield exploration, drilling and process equipment, including butnot restricted to pipelines, process equipment, vessels and tubulars.

More particularly, one embodiment of the present invention is a newhydrotest combination chemical formulation system for demonstrablyefficient (synergistic) and simple application where one single productcan be applied to perform the four essential roles of a hydrotestchemical; oxygen scavenging, biocidal activity, traceability through useof a dye, and microbially induced corrosion (MIC) inhibition.

BACKGROUND OF THE INVENTION

Towards the end of the construction phase of a piece of oilfieldequipment, or after rehabilitation of an existing piece of equipment, itis often necessary to pressure test this equipment for integrityassurance at a pressure above that of its designed working pressure.Pressures are typically conducted at 125% of the planned maximumallowable operating pressure, but may range from 100% to 150%. Theduration of the hydrostatic pressure tests may vary depending on thesystem being tested and the relevant codes and schedules of piping andequipment (Powell, D. E., Melancon, B., and Winters, R. H., (2011)Guidelines When Conducting Hydrostatic Pressure Tests and Management ofExtended Dwell Times Through Dry/Wet Lay-Ups. Paper 11082).

Pressure testing is typically performed with water (termed hydrostatictesting). After the pressure test is completed it is not unusual for thehydrotest fluid to remain in the tested equipment for an extended periodof time. The fluid used for hydrotesting can be extremely varied inquality and source. In offshore facilities, seawater is invariably used.On land it can be brackish water, river water, lake water or pond water.In both onshore and offshore scenarios, it is also possible for recycledproduced water or aquifer water to be used; use of potable water anddrill water has also been commonplace. It is possible for any of thesewater sources to cause corrosion due to several different mechanisms:

-   -   Oxygen induced corrosion: most of the water types used for        hydrotesting are fully saturated (up to and beyond 8 mg/L) with        oxygen. This can cause flash rusting especially around welds        where the heat affected zones and weldment material are        particular susceptible.    -   Microbially induced corrosion: this is a major threat to        pipelines and storage tanks. While this may be limited during a        hydrotest because of a lack of nutrients (if fresh water is        used), any biofilm left behind after a hydrotest can further        proliferate after the equipment is commissioned resulting in        severe localized pitting corrosion (Little, B. J. and        Lee, J. S. (2007) [Microbially Influenced Corrosion. Wiley and        Sons, New York, 279 pp]). Under-deposit corrosion can also occur        as a result of MIC and biofilm build up.    -   Chloride induced corrosion: depending on the type of water used        for the hydrotest, general corrosion can be induced as a result        of increased electrolyte in the hydrotesting water.

The severity of the corrosion from the above three mechanisms is reliantupon the quality of water and source of water used for the hydrotest.

Single functionality hydrotest chemicals generally include oxygenscavengers such as ammonium bisulfite or sodium bisulfite; biocidesinclude Pentane-1,5-dial (Pentanedial, Glutaraldehyde, Glutaric aciddialdehyde, Glutaric aldehyde, Glutaric dialdehyde, 1,5-Pentanedial) orTetrakis(hydroxymethyl)phosphonium sulfate (THPS); corrosion inhibitorstypically include proprietary quaternary ammonium compounds, for exampleas described by Janak and Ludensky, WO 2013/007811 A1. The varioussingle functionality chemicals are also discussed by Penkala, J. E.,Fichter, J., and Ramachandran, S. (2010) [Protection AgainstMicrobiologically Influence Corrosion by Effective Treatment andMonitoring During Hydrotest Shut-In. Paper 10404], Ruschau, G., Huang,W., Sullivan, E., and Surkein, M. (2011) [Hydrotesting of LNG TanksUsing Untreated Brackish Water. Paper 11216], Powell, D. E., Melancon,B., and Winters, R. H. (2011) [Guidelines When Conducting HydrostaticPressure Tests and Management of Extended Dwell Times Through Dry/WetLay-Ups. Paper 11082] and Huang, W., Xu, D., Ruschau, G., Wen, J.,Homemann, J., and Gu, T. (2012) [Laboratory Investigation of MIC Due toHydrotest using Seawater and Subsequent Exposure to Pipeline Fluids withand without SRB Spiking. Paper C2012-0001226].

Prasad, U.S. Pat. No. 6,815,208 discloses a method for treatinghydrotest water to inhibit oxygen corrosion, MIC, and allow the safedischarge of the water. The patent describes a combination treatmentplan (using individual chemicals sequentially) that enables reduction ofbiocide usage by increasing the pH of the hydrotest fluid. The methodincludes adding an oxygen scavenger to removed oxygen and prevent oxygencorrosion; raising the hydrotest water pH, typically in excess of pH9.5; then adding a biocide in a reduced amount; and then adding a scaleinhibitor to inhibit scale that could have been induced by increasingthe pH to alkaline conditions.

Cook, U.S. Pat. No. 4,501,667 describes a process for conditioning metalsurfaces to inhibitor corrosion and/or scale deposition using a watersoluble salt. The patent claims use of a combination scale and corrosioninhibitor to be used in an aqueous system that can adsorb onto metalsurfaces thereby protecting them from scale deposition and corrosionattack.

Cuisia, et al., U.S. Pat. No. 5,244,600 discloses a method forinhibiting or preventing corrosion of metals in contact with an aqueoussystem containing dissolved oxygen and adding an oxygen scavenger to thesystem having the formula (C)_(n)H₂OH—COOH wherein n is 5 or 6, lactonederivatives, or its water soluble salts, in an amount effective tosubstantially remove dissolved oxygen.

Bryan, et al., U.S. Pat. No. 5,385,896 claims the use of phosphoniumsalts, such as Tetrakis hydroxymethyl phosphonium (THP) salts, andaldehydes, such as formaldehyde, exhibiting synergistic biocidalactivity. Use of combinations of different biocides can lead tosynergism when compared to the individual components.

Craig, U.S. Pat. No. 2003/0057401 discloses water-soluble corrosioninhibitor compositions, useful for inhibiting corrosion of an oil or gaspipeline. The compositions contain a corrosion inhibitor component and abinding agent component and may be applied to the internal surface of apipeline during or before their construction. When the pipeline isflooded with hydrotest fluid, the compositions dissolve over a period oftime and inhibit internal corrosion of the pipe. This patent usesbinding agents such as polyacrylamide, polyvinyl alcohol or fish glue to“encapsulate” corrosion inhibitor chemistries into a bound material thatcan be applied to pipeline pre-commissioning and then release into thehydrotest fluid slowly over time.

Janak and Ludensky, WO 2013/007811 describes the prevention and removalof biofilm growth and microbially induced corrosion in gas and/orliquids steams in industrial process systems, such as oil and gasproduction and gathering systems. The method comprises the addition ofone or more quaternary ammonium compounds ((R¹R²R³R⁴N⁺)_(n)X^(n-)) suchthat the treatment regime involves an initial batch treatment as micelleforming concentrations of that are followed by batch or continuoustreatment of the same compounds or alternate biocides.

Although a number of hydrotest chemicals and systems for use in oil andgas industry are known in the prior art, there is a continued need formore effective products and systems. Especially there is still a needfor chemical systems that perform multiple tasks during the hydrotest.This is especially true for the more and more common place subseasystems that are very challenging to treat with combinations of singleapplication chemicals. The current invention describes the use ofcomplex blends of chemicals that are able to perform no less than 4different functions in a hydrotest, including oxygen scavenging,corrosion inhibition, biocidal activity and leak detection via the useof visual dyes.

SUMMARY OF THE INVENTION

It has been found that a a new hydrotest combination chemicalformulation system including an oxygen scavenger, biocide, microbiallyinduced corrosion inhibitor, general corrosion inhibitor, localized(pitting) corrosion inhibitor and a visual leak detection dye can beused in pressure testing operations for upstream and downstream oil andgas operations, pipeline commissioning and repair activities, processvessel pressure testing, subsea hydrotesting and process tubularhydrotesting activities.

The primary object of the invention is to provide a simple to use,single use, hydrotest formulation system with strong oxygen scavengingproperties, biocidal properties to negate any corrosion due tobiological activity, corrosion inhibition due to adsorption to the metalsurface and visual leak detection due to the presence of a dye. This hasalso been formulated in an environmentally acceptable package, aslegislated by many different regulatory bodies worldwide (e.g. CEFAS,NICNAS, TSCA, DSL, etc.). This unique combination has superiorperformance to formulations and individual chemicals disclosed in theprior art. Yet another objective of the present invention is to providea formulation suitable for application under extreme conditions, such asvery high salinities as well as high (up to 100° C.) or low temperatures(down to −10° C.) that are sometimes encountered during the hydrotestingof equipment. The formulations described in this invention can beubiquitously used in all types of previously described hydrotest fluidmatrices such as, but not limited to, seawater, drill water, potablewater, river water, pond water, lake water, aquifer water, producedwater, and brines.

Other objects and advantages of the present invention will becomeapparent from the following descriptions, wherein, by way ofillustration and example, an embodiment of the present invention isdisclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the embodiments of the present invention isprovided herein below, by way of example only, with reference to theaccompanying drawings, in which:

FIG. 1 represents the oxygen scavenging efficacy of the invention whencompared to a standard chemistry at 25° C. in seawater showing analogousperformance to standard ammonium bisulfite alone.

FIG. 2 represents the oxygen scavenging efficacy of the invention whencompared to a standard chemistry at 4° C. in seawater showingimprovement over Formulation 3 and analogous performance to standardammonium bisulfite alone.

FIG. 3 represents the oxygen scavenging efficacy of the invention at 25°C. in fresh water showing an improvement over the typical Formulation 3and standard ammonium bisulfite alone.

FIG. 4 represents the Linear Polarization Resistivity (LPR) trendsdisplaying corrosion inhibition efficacy of the invention compared totypical prior art and industry standard corrosion inhibitors.

FIG. 5 represents the Most Probably Number (MPN) bacterial kill efficacyof formulations considered to be prior art.

FIG. 6 represents the Most Probably Number (MPN) bacterial kill efficacyof the best performing prior art chemistry and the newly inventedproducts all added at 500 ppm based on the as manufactured formulation.

FIG. 7 represents the DNA results of alkyldimethyl ammonium chlorideformulation at 4° C. and 25° C. with both controls shown.

FIG. 8 represents the DNA results of the invention formulation 1 at 4°C. and 25° C. with both controls shown.

FIG. 9 represents the DNA results of the invention formulation 2 at 4°C. and 25° C. with both controls shown.

FIG. 10 represents the DNA results of glutaraldehyde 50% at 4° C. and25° C. with both controls shown.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a first aspect, this invention relates to a composition, comprising

a) at least one quaternary ammonium compound of the formula (I)

-   -   wherein    -   R is a C₅ to C₂₁ aliphatic hydrocarbon group,    -   X is an anionic counter ion, and    -   R^(a), R^(b) are selected from the group consisting of hydrogen,        methyl, ethyl, allyl, propyl, butyl, phenyl or benzyl residues,

b) ammonium bisulfite, sodium bisulfite, or both

c) glutaraldehyde, THPS, or both, and

d) at least one organic dye.

In a further aspect, this invention relates to a process for pressuretesting oilfield equipment using an aqueous pressure medium, the processcomprising adding to the aqueous pressure medium a composition,comprising

a) at least one quaternary ammonium compound of the formula (I)

-   -   wherein    -   R is a C₅ to C₂₁ aliphatic hydrocarbon group,    -   X is an anionic counter ion, and    -   R^(a), R^(b) are selected from the group consisting of hydrogen,        methyl, ethyl, allyl, propyl, butyl, phenyl or benzyl residues,

b) ammonium bisulfite, sodium bisulfite, or both

c) glutaraldehyde, THPS, or both, and

d) at least one organic dye.

In a further aspect, this invention relates to the use of a composition,comprising

a) at least one quaternary ammonium compound of the formula (I)

-   -   wherein    -   R is a C₅ to C₂₁ aliphatic hydrocarbon group,    -   X is an anionic counter ion, and    -   R^(a), R^(b) are selected from the group consisting of hydrogen,        methyl, ethyl, allyl, propyl, butyl, phenyl or benzyl residues,

b) ammonium bisulfite, sodium bisulfite, or both

c) glutaraldehyde, THPS, or both, and

d) at least one organic dye,

as an additive to an aqueous pressure medium in a process for pressuretesting oilfield equipment using said aqueous pressure medium.

Detailed descriptions of the preferred embodiments are provided herein.It is to be understood, however, that the present invention may beembodied in various forms. Therefore, specific details disclosed hereinare not to be interpreted as limiting, but rather as a basis for theclaims and as a representative basis for teaching one skilled in the artto employ the present invention in virtually any appropriately detailedsystem, structure or manner.

The inventors have found new formulated hydrotest chemical systems,including an oxygen scavenger, biocide, corrosion inhibitor and visualdye, wherein the systems are substantially synergistic, multifunctionaland are capable of removing oxygen, controlling general corrosion,localized (pitting) corrosion, microbially induced corrosion,controlling bacterial cultures and being readily detectable visually, orunder ultra-violet light. The new hydrotest systems and uses thereofafford rapid control of oxygen, bacteria, and corrosion while beingvisually detectable in equipment and pipes required to be pressuretested.

The inventors have found that the inventive compositions provideenhanced performance over that of anything in the prior art or indeedthe individual components themselves. This is especially the case forthe rate of corrosion rate reduction over time, oxygen scavenging andthe resistance against high salinity and stability in a largetemperature range, compared to prior art hydrotest chemicals andsystems.

In certain embodiments, the new stable, hydrotest systems include aquaternary ammonium compound or a plurality of quaternary ammoniumcompounds, a biocide component or a plurality of biocide components, aco-solvent subsystem and a solvent system including glycols, glycolethers, alcohols, and water, where dye or dyes includes a number ofdifferent xanthene derivatives.

If in the following the expression “subsystem” is mentioned, thisexpression refers to a component of the claimed composition wherein morethan one species of the generically described group of compounds of therespective component is present.

Component a) is quaternary ammonium compound corrosion inhibitorincluding at least one compound of the formula (I).

In a preferred embodiment, R is selected from C₅ to C₂₁, more preferablyC₈ to C₁₄ linear or branched alkyl or alkenyl residue.

Particularly preferred are compounds of formula (I) wherein R^(a) andR^(b) are methyl or ethyl. Examples of such compounds are alkyldiethylammonium chloride with C₅ to C₂₁ alkyl groups, didecyldimethyl ammoniumchloride and didecyldimethyl ammonium bicarbonate.

In another preferred embodiment, X is selected from the group consistingof acetate, polycarboxylates, chloride, bromide, iodide, bicarbonate,carbonate, sulfate and methylsulfate. Particularly preferable arechloride, bicarbonate and carbonate.

In another preferred embodiment, R^(a) and/or R^(b) are independentlyselected from the group consisting of hydrogen, methyl, ethyl, allyl,propyl, butyl, phenyl or benzyl residues.

The quaternary ammonium compound subsystem can additionally includealkyl quaternary compounds such as Alkyltrimethylammonium chloride (e.g.N-Alkyl(C₁₂-C₁₆)—N,N,N-trimethylammonium chloride) and alkyl arylquaternary compounds such as Alkylbenzyldimethylammonium chloride asthese in particular have shown superior adsorption properties whichcreates enhanced performance in this application. Compounds which may beadditionally included correspond to the formula (II)

wherein

-   -   R is a C₅ to C₂₁ aliphatic hydrocarbon group, and preferably is        selected from C₅ to C₂₁, more preferably C₈ to C₁₄ linear or        branched alkyl or alkenyl residues,    -   X is an anionic counterion, preferably selected from the group        consisting of acetate, polycarboxylates, chloride, bromide,        iodide, bicarbonate, carbonate, sulfate and methylsulfate, and        particularly preferably from chloride, bicarbonate and        carbonate, and    -   R^(a), R^(b) and R^(c) are independently a C₅ to C₂₁ aliphatic        hydrocarbon group, preferably selected from C₅ to C₂₁, more        preferably C₈ to C₁₄ linear or branched alkyl or alkenyl        residues, particularly preferred selected from hydrogen, methyl,        ethyl, allyl, propyl, butyl, phenyl and benzyl residues.

As component b), the inventive composition comprises an oxygen scavengercomponent. The oxygen scavenger includes ammonium bisulfite, sodiumbisulfite or both. In a preferred embodiment, the oxygen scavenger canadditionally include sodium sulfite, hydrazine, diethylhydroxylamine(DEHA), carbohydrazide, erythorbic acid, methylethylketoxime (MEKO), andhydroquinone.

As component c) the inventive composition comprises a synergisticbiocidal component, which is selected from glutaraldehyde, THPS and amixture of glutaraldehyde and THPS. The addition of glutaraldehyde, THPSor both enables a full synergy with the corrosion inhibitor present inthe multi-component system. Whereas, some of the quaternary ammoniumcompounds listed in a) above also can be registered biocides and provideeven greater synergy in the formulation. In addition, other biocidesselected from the group consisting ofTetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione (Dazomet);N,N′-Methylene bis(5-methyl oxazolidine) (MBMO);1,3-Bis(hydroxymethyl)-5,5-dimethylimidazoline-2,4-dione (DMDMhydantoin) may be present in the inventive composition.

As component d) the inventive composition comprises a dye. Preferreddyes are selected from the group consisting of fluorescein, disodiumsalt (9-o-Carboxyphenyl-6-hydroxy-3-isoxanthone, disodium salt); C.I.45350 disodium salt; C.I. Acid Yellow 73; D&C Yellow No. 8; Disodium6-hydroxy-3-oxo-9-xanthene-o-benzoate; fluorescein sodium; xanthene dyeas shown in Formula (IV) below;9-(2-carboxyphenol)-3,6-bis(diethylamino)-xanthium chloride (RhodaminB); C.I. 45170; Basic Violet 10 as shown in Formula (V) below.

The dye provides essential functionality to the formulation insofar aswhen failure of the pressure test occurs, the dye provides a visualrepresentation of the leak. Even small concentrations of these dyes canbe detected due to excitation under specific wavelengths of non-visiblelight (e.g. UV-light). The current invention preferably utilizes specialcosolvent systems, as described in e) and f) below, in order to enablefull brine and thermal stability of these dyes in the formulation.

As optionally present component e) the inventive composition preferablycomprises a co-solvent subsystem, including at least one alcohol. In apreferred embodiment, this alcohol of the solvent blend may be amonohydric alcohol or a diol. It is believed that the alcohol serves asa coupling agent between the other components in the formulation,thereby stabilizing the hydrotest chemical. The alcohol also lowers thefreezing point of the hydrotest chemical. Although propylene glycol ispresently more preferred, alternative suitable alcohols include primary,secondary and tertiary monohydric alcohols, with between 1 and 20 carbonatoms and diols with between 2 and 20 carbon atoms, such as isopropanol,t-butanol, n-butanol, n-pentanol, n-hexanol, n-octanol and pentane-diol.

As optionally present component f) the inventive composition preferablycomprises a mutual solvent selected from the group consisting of2-ethyl-hexanol, ethylene glycol ether of 2 ethyl-hexanol, polyethyleneglycol ethers of 2 ethyl-hexanol and propylene glycol for bettercoupling between the components of the formulation and lowering thefreezing point of the hydrotesting chemical system. The polyethyleneglycol components preferred in this embodiment range in molecular weightfrom 200 to 2,500 Daltons.

As optionally present component f) the inventive composition preferablycomprises water, whereas the water can be fresh water, produced water orbrine.

The composition of one embodiment of the present invention is preferablyprepared by combining

10 to 70 wt.-% of the quaternary ammonium compounds described in a)above,

1 to 50 wt.-% of the oxygen scavenger described in b) above,

1 to 20 wt.-% of the synergistic biocide described in c) above,

1 to 20 wt.-% of the dye described in d) above,

0, optionally 1 to 30 wt.-% of solvents described in e) and f) above,

optionally with the remainder being water as described in g) above.

1 to 25 wt.-% of other compounds selected from the group consisting ofpolyethylene glycol ethers (varying in molecular weight from 200 to2,500 Daltons) and inorganic salts may be added to lower the freezingpoint of the composition, improve stability and performance whennecessary.

The hydrotesting chemical systems of this invention are adapted to beadded to hydrotest waters for application in pipelines and vessels inconcentrations between 100 and 2,000 mg/L. The exact concentration willdepend on the hydrotest water type, static conditions, materials ofconstruction of the medium being hydrotested, quality of the water beingused to hydrotest and length of time protection is to be provided to thehydrotest water. At this concentration range, the system provides oxygenscavenging, corrosion protection, biocidal activity and suitablevisibility due to the dye in order to improve the integrity of the mediabeing hydrotested. Most of the commercially available hydrotest systemsfor these applications are either single components added sequentiallyto a hydrotest job, or have been formulated with components that onlyprovide limited functionality, when compared to the currentmulti-functionality providing composition of the instant invention, orthe treating solution is of limited salinity tolerance or temperaturestability. Another problem related to the prior art systems is that thekinetics of functionality are slow, either oxygen scavenging takingseveral days or corrosion rate reduction taking many hours or limitedbiocidal activity due to interactions between the biocide components andoxygen scavenger. For example, it is well known that THPS reacts withammonium bisulfite at high concentration, glutaraldehyde reacts withammonium bisulfite at high concentration.

The present invention also involves a process for conventional andnon-conventional applications using the compositions above for pipeline,vessel, tubular, well, or annular hydrotests. The composition of thepresent invention is preferably used at 100 to 2,000 mg/L of hydrotestfluid. The injected water may be fresh water, produced water, KClsolution, NaCl solution, river water, brackish water, lake water, pondwater, or the combination of two or more of these. In general anyaqueous liquid used for hydrotesting may be employed. The composition ofthis invention is added to the water or injection brine and injectedinto the hydrotest to provide oxygen scavenging, corrosion protection,biocidal control and visual detectability. The injection fluid maycontain, in addition to the composition of the instant invention, otheringredients known to those familiar with the art including but notrestricted to acids, dispersants, viscosifiers, lubricity agents, scaleinhibitors, friction reducers, crosslinker, surfactants, pH adjuster,iron control agents, breakers; this is especially true if produced water(or recycled water) is used to perform the hydrotest.

Employing the composition of the instant invention improvesnullification of the hydrotest water to render it benign andnon-corrosive and damaging to the integrity of the equipment it will beused to hydrotest, thus allowing better integrity management andcontrol, improved oxygen scavenging, biological control, surfacecorrosion inhibition protection and visual detectability. Otherapplications of the formulation of the instantaneous invention includetreating water for downhole injection for pressure support, treatment ofwater for drilling and work-over use, wettability alteration and wellcleanout.

EXAMPLES

If not stated otherwise, references to % or ppm mean wt-% or wt.-ppmthroughout this specification.

Example 1 Compositions

Hydrotest formulations illustrating different compositional aspects ofthis invention are listed in Table 1.

TABLE 1 List of compositions of this invention. Formulation # 1 # 2 # 3Water [wt.-%] 10 20 20 Glycol [wt.-%] 0 0 0 DDAC [wt.-%] 20 20 0 ABS[wt.-%] 30 30 30 Rhodamin B [wt.-%] 10 0 0 Glutaraldehyde [wt.-%] 0 0 0ADMAC [wt.-%] 0 0 50 ATMAC [wt.-%] 30 30 0

The different materials are as follows:

-   1.) potable water (component g)) is either potable, deionized, salt    water or 3% KCl.;-   2.) glycol (component e)) is used as a co-solvent and to decrease    the freezing point, this can be mono-ethylene glycol, triethylene    glycol, or propylene glycol in these formulations specified,    monoethyelene glycol was used throughout;-   3.) quaternary ammonium compounds (component a)) such as DDAC    described by Formula I, alkyl (in this case lauryl) dimethyl    ammonium chloride (ADMAC), N-alkyl, C₁₂₋₁₆-M,N,N,trimethyl ammonium    chloride (ATMAC), as described by formula II, used as a corrosion    inhibitor and/or biocidal component;-   4.) oxygen scavenging component (component b)) such as ammonium    bisulfite (ABS) which is the preferred embodiment;-   5.) a visual dye (component d)) such as Rhodamin B which is the    preferred embodiment;-   6.) a synergistic biocidal component (component c)) such as    glutaraldehyde in order to provide a more effective biocidal    activity without compromising the overall formulation stability or    oxygen scavenging efficacy: glutaraldehyde is the preferred    embodiment.

Example 2 Oxygen Scavenging Efficacy

Oxygen scavenging efficacy was evaluated using a real-time orbisphereoxygen sensor with data logging. The test equipment consisted of astirrer plate and stirrer bar, a 1 liter test cell, circulation pump,flow chamber, oxygen sensor and data logger. Test work was performedusing potable water taken from the mains water supply in The Woodlands,Tex. and then using filtered seawater taken from Galveston, Tex. Testingwas performed at 4° C. and 25° C. by wrapping the test cell with amonoethylene glycol circulator chiller jacket. A carbon steel stirrerbar was added to the test cell to replicate turbulence that would becreated upon pumping the hydrotest fluid using the metallurgy of atypical pipeline. A non-pulsing circulation pump was set to circulatethe test fluid past the oxygen sensor at a rate of 10 mL·min⁻¹. Theoxygen sensor was calibrated prior to every new test run. Each test wasrun for a duration of 60 minutes with a 10 minute stabilization periodprior to the introduction of test chemical. Chemical was injected intothe test cell by means of a needle and syringe through a rubber stopperto minimize any oxygen ingress during this stage of the test. Throughoutthe test, oxygen levels were measured once every minute and the datacontinuously logged. The water chemistry composition has been given inTable 2 below:

TABLE 2 Seawater and freshwater chemical composition Seawater FreshwaterIon [mg/L] [mg/L] Sodium 13,917 2 Potassium 460 0.05 Calcium 428 10.5Magnesium 979 4.2 Strontium 7 0 Sulfate 2,960 0.5 Chloride 19,800 3.9

All tests of the new formulations (detailed in Table 1) were benchmarkedagainst prior formulations; in this case a product termed as an ADMACbased product that has 50% ADMAC (specifically lauryl dimethyl ammoniumchloride), 30% ammonium bisulfite and 20% water, herein referenced asFormulation 3 and detailed in Table 1. Furthermore ammonium bisulfitewas used as a benchmark and the activity matched up to 30% which is theconcentration used in all the formulations. Therefore all testing hadthe same concentration of oxygen scavenging component with the onlyvariable being the other components of the formulation. All tests used500 ppm of the product, which resulted in the same oxygen scavengerconcentration being used in all tests.

The results of testing oxygen scavenging potential in seawater at 25° C.are shown in the following table.

TABLE 3 Oxygen scavenging efficacy of the invention when compared to astandard chemistry at 25° C. in seawater showing analogous performanceto standard ammonium bisulfite alone 500 ppm 500 ppm 500 ppm BlankFormula- Formula- Formula- 500 ppm Time (ppm tion 3 tion 1 tion 2 ABS30% (minutes) O₂) ppm O₂) (ppm O₂) (ppm O₂) (ppm O₂) 0 7.218 6.272 6.4336.304 7.112 2 7.154 6.220 6.398 6.309 7.081 4 7.135 6.167 6.362 6.3317.029 6 7.054 6.109 6.340 6.328 7.084 8 7.014 6.064 6.297 6.289 7.066 107.001 6.007 6.224 6.264 7.061 12 6.958 0.192 0.210 0.208 0.052 14 6.9750.044 0.039 0.033 0.013 16 6.925 0.026 0.023 0.022 0.010 18 6.857 0.0170.016 0.016 0.009 20 6.829 0.012 0.012 0.012 0.008 22 6.757 0.009 0.0080.009 0.007 24 6.751 0.006 0.006 0.006 0.006 26 6.750 0.005 0.004 0.0050.005 28 6.747 0.003 0.003 0.003 0.004

It should be noted that all testing was performed so that theconcentration of oxygen scavenger was exactly the same in all tests sothe only variables were the counter components in the formulations, thisisolating the effects that combining components has upon the oxygenscavenging efficacy of the invented products. Therefore all formulationswere added at 500 ppm. As can be seen all formulations contained 30% ofammonium bisulfite and this is why ABS 30% was used as a benchmark. Theresults show analogous performance to the prior Formulation 3 andammonium bisulfite (ABS) 30% and also all formulated perform to the sameultimate level as ABS 30% alone. This clearly demonstrates that additionof the DDAC and DDABC quaternary ammonium compounds of Formulation 2does not have any deleterious effects on oxygen scavenging efficacy.Furthermore, adding a dye into the formulation as well as the DDAC andDDABC, as is the case with Formulation 1, has no further negativeeffects on oxygen scavenging efficacy. It should be noted thatscavenging in relatively warm seawater is not a very challengingenvironment to perform this testing in.

Therefore the following table shows the test performed in seawater butat 4° C. which is a far more challenging environment to scavenge oxygenfrom.

TABLE 4 Oxygen scavenging efficacy of the invention when compared to astandard chemistry at 4° C. in seawater showing improvement overFormulation 3 and analogous performance to standard ammonium bisulfitealone 500 ppm 500 ppm 500 ppm Blank Formula- Formula- Formula- 500 ppmTime (ppm tion 3 tion 1 tion 2 ABS 30% (minutes) O₂) (ppm O₂) (ppm O₂)(ppm O₂) (ppm O₂) 0 7.278 7.554 7.434 7.445 7.554 2 7.157 7.432 7.3107.243 7.452 4 7.153 7.361 7.188 7.088 7.357 6 7.195 7.309 7.071 6.9617.268 8 7.077 7.138 6.915 6.749 7.121 10 7.035 6.945 6.812 7.190 6.99712 7.014 2.224 3.599 2.684 2.125 14 6.987 0.527 0.956 0.645 0.454 166.966 0.312 0.301 0.289 0.269 18 6.934 0.175 0.110 0.165 0.064 20 6.9110.142 0.048 0.081 0.047 22 6.884 0.080 0.033 0.037 0.029 24 6.872 0.0710.036 0.015 0.009 26 6.851 0.071 0.024 0.005 0.003 28 6.823 0.032 0.0260.002 0.002

Here it can be seen that Formulation 1 and Formulation 2 outperformFormulation 3 currently employed in the industry and performs as well asABS 30% alone. The undyed Formulation 2 scavenges oxygen to the same lowlevel of <0.01 ppm as seen in the 25° C. test and when adding dye as inFormulation 1, the scavenging still outperforms the commerciallyavailable (non-dyed) Formulation 3. The most challenging test wasperformed on fresh water, and as can be seen from the following table.

TABLE 5 Oxygen scavenging efficacy of the invention at 25° C. in freshwater showing an improvement over the typical Formulation 3 and standardammonium bisulfite alone 500 ppm 500 ppm 500 ppm Blank Formula- Formula-Formula- 500 ppm Time (ppm tion 3 tion 1 tion 2 ABS 30% (minutes) O₂)(ppm O₂) (ppm O₂) (ppm O₂) (ppm O₂) 0 8.342 8.294 8.393 8.352 8.314 28.362 8.298 8.352 8.395 8.346 4 8.752 8.352 8.298 8.285 8.310 6 8.3818.393 8.294 8.296 8.265 8 8.369 8.383 8.250 8.251 8.345 10 8.326 8.1788.164 8.103 8.302 12 8.216 7.618 7.547 7.478 7.612 14 8.211 6.783 6.7966.478 6.674 16 8.187 5.734 5.894 5.587 5.585 18 8.147 4.911 4.989 4.8414.732 20 8.102 4.300 4.247 4.376 4.115 22 8.069 3.715 3.854 3.459 3.76524 8.014 3.330 3.379 3.327 3.195 26 7.914 3.028 3.044 3.010 3.027 287.813 2.627 2.783 2.473 2.546 30 7.810 2.330 2.518 2.168 1.863 32 7.7121.873 2.249 2.006 1.516 34 7.671 1.223 1.966 1.860 1.173 36 7.587 0.9071.668 1.550 0.857 38 7.469 0.762 1.357 1.200 0.654 40 7.403 0.618 1.0181.100 0.436 42 7.315 0.471 0.659 0.900 0.349 44 7.257 0.313 0.266 0.5000.215 46 7.182 0.170 0.172 0.300 0.134 48 7.113 0.143 0.132 0.200 0.11950 7.068 0.127 0.108 0.172 0.096 52 7.003 0.117 0.093 0.132 0.087 546.912 0.109 0.082 0.108 0.063 56 6.862 0.103 0.075 0.093 0.055 58 6.7310.099 0.072 0.082 0.050 60 6.649 0.095 0.066 0.075 0.480

As expected, scavenging for all products occurred slower than withseawater. Formulation 1 and Formulation 2 continued to outperform theFormulation 3 in the testing, both scavenging down to a lower levelafter 60 minutes.

Example 3 Corrosion Inhibition Efficacy

The following table shows the corrosion inhibition efficacy of theinvention at 25° C. in a seawater system (Table 2 shows the waterchemistry used for seawater).

TABLE 6 Summary of LPR measured corrosion protection of the inventionInitial corrosion Inhibited corrosion Inhibition rate rate EfficiencyTest [mm/year] [mm/year] [%] 500 ppm 1.009 0.002 99.8 Formulation 3 500ppm 1.194 0.003 99.8 Formulation 1 500 ppm 0.999 0.002 99.8 Formulation2 250 ppm 1.158 0.015 98.7 Formulation 3 250 ppm 1.217 0.009 99.3Formulation 1 250 ppm 1.106 0.010 99.1 Formulation 2 100 ppm 1.291 0.19784.7 Formulation 3 100 ppm 1.185 0.104 91.2 Formulation 1 100 ppm 1.1490.098 91.5 Formulation 2

A low shear Linear Polarization Resistivity (LPR) electrochemicaltechnique was used to measure the corrosion rate. The blank readingshowed a very high initial corrosion rate of 1 mm·yr⁻¹. This lowersslightly during the course of the test, as expected as a slightlypassivating film of corrosion deposits is established on the carbonsteel electrodes. The inhibited tests used the same prior Formulation 3(as used in previous testing) and the embodiments of the invention asFormulation 1 and Formulation 2. It can be seen that when adding 500 ppmof the formulations the corrosion rate was significantly reduced in allcases. However, it can be seen that Formulation 1 and Formulation 2outperformed Formulation 3 standard in terms of reducing the corrosionrate quicker, clearly seen during the first 1 hour period, and thenresulting in a lower overall corrosion rate. This has been attributed tothe better surface chemi-sorption properties of the DDAC and DDABC usedin the embodiments of the invention formulations when compared to theother standard tested material.

Different concentrations of the products were used and the above exampleand the further tests have also been summarized in Table 6. It can beseen that as the dose rate is reduced, the protection of the priorFormulation 3 drops and <85% protection is afforded with 100 ppm ofchemical whereas >90% inhibition is offered by both Formulation 1 andFormulation 2.

Example 4 Most Probable Number (MPN) Biocidal Properties

The Most Probably Number technique using a bacterial enumerationtechnique was performed, as described in NACE International Standard TMP194-2004. Complex mixed consortia were isolated from seawater andsubjected to the chemicals being tested. All chemicals were applied atthe same active concentration. Surviving cells were assayed afterexposure periods of 1, 7 and 28 days to the numbers compared with acontrol which received no treatments. The bottle tests were carried outusing two mixed consortia—Sulfate Reducing Bacteria (SRB) and GeneralHeterotrophic Bacteria (GHB) that also measured Acid Producing Bacteria(APB) enriched from seawater. Aliquots of the water (1 mL) wereinoculated into SRB culture medium and GHB culture medium (Phenol RedDextrose broth) respectively and sub-cultured twice. The cultures usedin the tests were incubated at 30° C. for five days; these were thenused to supplement seawater to achieve 10³ to 10⁴ SRB cells per mL. Forthe trial one control bottle and four test bottles were set up. Thechemicals were added to the appropriate test bottles to give the finalconcentrations of each product as supplied. All chemicals were added sothat 500 ppm of active biocide was present in each test. The controlbottle contained seawater only with no added chemical. At each timepoint, (one, seven and twenty-eight days), a sample was removed fromeach test bottle and the control bottle and used to inoculate the MPNvials. Bacterial counts were performed using the triplicate MostProbable Number method (triplicate MPNs). The inoculated MPN vials wereincubated at 30° C. for 7 days for GHB and APB and 28 days for SRB.Results have been reported as cells per mL.

The following table shows the results of testing different biocidalcomponents that can formulate with oxygen scavenger and can beconsidered to be prior art.

TABLE 7 Most Probably Number (MPN) bacterial kill efficacy offormulations considered to be prior art. All chemicals were formulationscontaining ammonium bisulfide with the named biocide and added at 500ppm active biocide Test GHB per mL APB per mL SRB per mL Time 0 2.5E+032.5E+03 4.5E+04 Control 24 h 9.5E+04 9.5E+02 4.5E+03 Formulation 3 24 h6.0E+00 6.0E+00 1.0E+00 Dazomat 24 h 4.5E+02 2.5E+02 2.5E+04 MBMO 24 h9.5E+03 7.5E+02 9.5E+03 DMDM hydantoin 24 h 9.5E+03 4.5E+02 9.5E+04Control 7 d 7.5E+05 7.0E+01 1.0E+04 Formulation 3 7 d 4.0E+01 1.5E+011.0E+00 Dazomat 7 d 4.5E+03 2.5E+02 2.0E+02 MBMO 7 d 4.5E+03 7.5E+024.0E+01 DMDM hydantoin 7 d 9.5E+05 2.5E+02 9.5E+02 Control 28 d 4.0E+049.5E+01 1.0E+04 Formulation 3 28 d 2.0E+01 2.0E+01 1.0E+00 Dazomat 28 d2.5E+05 4.5E+02 1.0E+00 MBMO 28 d 2.5E+02 4.5E+01 1.0E+00 DMDM hydantoin28 d 2.5E+05 9.5E+04 4.5E+06

The following active biocides contained in hydrotest formulations weretested: Tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione (Dazomet);N,N′-Methylene bis(5-methyl oxazolidine) (MBMO);1,3-Bis(hydroxymethyl)-5,5-dimethylimidazoline-2,4-dione (DMDMhydantoin); and Formulation 3. It can be seen from the results thatFormulation 3 showed the best effect against planktonic GHB, APB and SRBpopulations after all time exposures, but after an exposure time numbersslightly recovered again. All other formulated biocides tested appearedto be much less effective against GHB, APB and SRB populations withpopulations recovering again after an exposure time of 28 days.

Formulation 3 resulted in a 4 log reduction of planktonic GHB and SRBafter an exposure time of 24 hours and a 2 log reduction of APB numbers.Both GHB and APB numbers recovered slightly by 1 and 0.5 log after anexposure time of 7 to 28 days. It can be seen that SRB populations neverregrew and therefore it can be concluded that Formulation 3 had a longterm effect on SRB numbers.

Dazomet reduced GHB numbers by 2.5 log, but did not result in asignificant reduction of APB numbers (0.5 log) or SRB numbers after anexposure time of 24 hours. Both GHB and APB numbers recovered againafter 7 days. Again, SRB numbers are low after an exposure time of 7 and28 days, showing that Dazomet has a long term effect on SRB numbers.

The exposure to MBMO resulted in a 1 log reduction of GHB numbers afteran exposure time of 24 hours, and a further 2 log reduction after 28days. The exposure to MBMO did not show to be effective against APB andSRB numbers up to 7 days but a longer term effect was present afterextended exposure of 28 days as SRB are reduced to a minimum and GHBreduced relative to the control, although APB were still very active.

DMDM hydantoin resulted in a 1 log reduction of GHB numbers after anexposure time of 24 hours, but numbers recovered again after 7 and 28days. APB and SRB showed no effect after an exposure time of 24 hours,but increased over the course of trial. Although the SRB control was lowafter 7 and 28 days, the increase in the test bottles can be seen as atrue increase.

A second set of MPN data was generated using the best performing product(Formulation 3) from the first MPN test and this time growing thecultures to a 10⁶ to 10⁷ cells per mL level in order to really test thebacterial control levels in Formulation 3 alongside the embodiments ofthe invention Formation 1 and Formulation 2; the results can be seen inthe following table.

TABLE 8 Most Probably Number (MPN) bacterial kill efficacy of the bestperforming prior art chemistry and the newly invented products all addedat 500 ppm based on the as manufactured formulation. Test and timeelapsed GHB per mL APB per mL SRB per mL Time 0 2.0E+05 2.0E+05 1.1E+07Control 24 h 1.1E+07 4.5E+06 1.4E+07 Formulation 3 24 h 7.0E+02 7.0E+029.5E+03 Formulation 2 24 h 4.5E+01 4.5E+01 4.5E+01 Formulation 1 24 h7.0E+01 7.5E+01 9.5E+01 Control 7 d 1.4E+07 4.5E+05 1.4E+07 Formulation3 7 d 7.5E+04 7.5E+04 1.0E+00 Formulation 2 7 d 2.5E+04 2.5E+04 1.0E+00Formulation 1 7 d 3.5E+04 1.5E+04 1.0E+00 Control 28 d 4.5E+06 2.5E+051.4E+07 Formulation 3 28 d 4.5E+05 4.5E+05 1.0E+00 Formulation 2 28 d2.5E+04 4.5E+04 1.0E+00 Formulation 1 28 d 1.5E+04 1.5E+04 1.0E+00

All products reduced planktonic SRB numbers by 2 to 3 logs after 24hours of exposure. All chemical formulations tested reduced the SRBnumbers further, over 7 logs in total (when compared to the control) tobelow the detection limit, these cell numbers remained below detectionlimit after an exposure time of 28 days. All three biocides under testgave initial reduction of more than 4 logs in planktonic GHB and APBnumbers after 24 hours of exposure. Both GHB and APB numbers increasedagain after an exposure to all three biocides of 7 and 28 days.

It can be seen that both Formulation 1 and Formulation 2 showed superiorperformance to the best performing commercial formulation (Formulation3) by up to 2 orders of magnitude kill efficacy.

Example 5 Molecular Technique Biocidal Properties

Molecular techniques were performed on the best performing (Formulation3) commercial product and the embodiments of the invention Formulation 1and Formulation 2. This aim of the study was to investigate theefficiency of the biocides on inhibiting 5 species of bacteria in asimulated marine environment. This study was conducted over a 21 dayperiod and involved several marine species of bacteria which have allbeen previously linked with attributing to corrosion. In this study weaim to demonstrate the inhibition of bacterial growth across the timeperiod of incubation as a result of the biocide treatment. A control wasused in the testing and glutaraldehyde was selected for this role.

For each species 3 individual inoculums for each replicate were grownfrom an isolated single colony picked from agar plates. The species usedwere Desulfovibrio desulfricans (SRB), Shewanella putrefaciens (IRB),Thiobacillus thioparus (SOB), Pseudomonas aeruginosa (biofilm) andMethanolibacter arachidis (methanogens). Following 24 hours ofincubation on an orbital shaker, cells were centrifuged and the pelletedcells washed with phosphate buffered saline (PBS). Washed cells werethen suspended in PBS and measured to a set optical density via UVspectrometry at 600 nm. Each species was then used to inoculate culturesto give a final starter concentration of 0.01 at 600 nm. Each treatmentwas conducted in triplicate with each replicate being started atalternative time periods to reduce culture bias and human error. Threenegative controls and three positive controls were established for eachtemperature under study.

The trials were conducted in 125 mL Erlenmeyer flasks containing 75 mLof marine broth, which were subsequently autoclaved for 20 min at 121°C. All bottles were incubated at either 4° C. or 25° C. on an orbitalshaking platform at 150 rpm. Triplicate biocide treatments wereestablished at each temperature at concentrations of 500, 750 and 1000ppm. At each weekly interval, 2 mL samples were collected at 7, 14 and21 days from each bottle. These were subjected to a co-extraction of DNAwhich was measured with qPCR. The gene target in this study was 16s rDNAa conserved gene present in all bacteria and Achaea.

The following table shows the results of all DNA testing for the fourbiocides compared to positive controls.

TABLE 9 DNA results of tested formulations and standard biocides Dose 7day 14 day 21 day Rate Temp (DNA (DNA (DNA Test (ppm) (° C.) copies)copies) copies) Formulation 3 1000 4 1.22E+05 1.64E+06 2.41E+04Formulation 3 750 4 1.13E+06 1.85E+05 1.08E+06 Formulation 3 500 42.02E+06 1.68E+05 3.06E+06 Formulation 3 1000 25 9.23E+05 7.28E+043.73E+06 Formulation 3 750 25 1.50E+07 2.45E+05 3.75E+07 Formulation 3500 25 3.18E+04 1.70E+06 8.19E+06 Formulation 1 1000 4 1.46E+06 1.88E+061.74E+06 Formulation 1 750 4 1.17E+06 5.89E+05 9.99E+05 Formulation 1500 4 9.38E+05 6.97E+06 3.34E+05 Formulation 1 1000 25 6.33E+04 1.62E+043.04E+05 Formulation 1 750 25 1.92E+06 4.54E+04 1.33E+05 Formulation 1500 25 8.51E+06 1.38E+05 2.03E+04 Formulation 2 1000 4 2.52E+06 1.77E+051.81E+05 Formulation 2 750 4 2.00E+05 7.97E+04 3.79E+04 Formulation 2500 4 1.02E+04 1.01E+05 1.15E+05 Formulation 2 1000 25 3.24E+07 4.29E+051.76E+06 Formulation 2 750 25 3.79E+06 7.24E+04 1.14E+06 Formulation 2500 25 6.47E+06 4.78E+02 3.25E+06 Glutaraldehyde 500 4 2.60E+04 1.11E+087.22E+07 Glutaraldehyde 500 25 8.85E+04 1.00E+03 2.51E+10 Positivecontrol 0 4 6.12E+07 8.15E+07 4.59E+08 Negative control 0 4 3.07E+041.21E+03 7.61E+03 Positive control 0 25 3.22E+06 6.22E+07 9.53E+08Negative control 0 25 2.53E+05 3.63E+07 1.19E+11

Formulation 3 and Formulation 1 and Formulation 2 treated flasks growthis clearly inhibited with respect to the controls, the 25° C. control isabove the scale with a target copy number. The positive controlindicates the level of growth expected if no inhibitor is present. Theresults from the DNA testing for glutaraldehyde shows it to appearineffective at 4° C. during the first 14 days after which growth appearsto be inhibited. Growth in the 4° C. glutaraldehyde reached a 15.8 foldincrease when compared to the highest level seen in the other biocides.The data for glutaraldehyde at 25° C. clearly demonstrates theineffectiveness of this biocide at 500 ppm over a 3 week period. Thedata shows that growth has been inhibited to some degree compared to thecontrols however there are still large levels of growth being observedindicating that inhibition rather than total cell death has occurred.

When the highest count in the invention formulation biocide flasks at25° C. compared to the glutaraldehyde results there is a 670 foldincrease in copy number in the glutaraldehyde treated flask. It can alsobe seen that the embodiments of the invention Formation 1 andFormulation 2 show far more effective biocidal control than Formulation3.

1. A composition, comprising a) at least one quaternary ammoniumcompound of the formula (I)

wherein R is a C₅ to C₂₁ aliphatic hydrocarbon group, X is an anioniccounter ion, and R^(a), R^(b) are selected from the group consisting ofhydrogen, methyl, ethyl, allyl, propyl, butyl, phenyl or benzylresidues, b) ammonium bisulfite or sodium bisulfite, c) glutaraldehydeor THPS, and d) at least one organic dye.
 2. The composition accordingto claim 1, wherein R is a C₈ to C₁₄ aliphatic hydrocarbon group.
 3. Thecomposition according to claim 1, wherein R is a linear or branchedalkyl or alkenyl residue.
 4. The composition according to claim 1,wherein X is selected from the group consisting of acetate,polycarboxylates, chloride, bromide, iodide, bicarbonate, carbonate,sulfate and methylsulfate.
 5. The composition according to claim 1,wherein R^(a) and/or R^(b) are independently selected from the groupconsisting of hydrogen, methyl, ethyl, allyl, propyl, butyl, phenyl orbenzyl residues.
 6. The composition according to claim 1, wherein thecomposition additionally comprises alkyl quaternary compoundscorresponding to the formula (II)

wherein R is a C₅ to C₂₁ aliphatic hydrocarbon group, X is an anioniccounterion and R^(a), R^(b) and R^(c) are independently a C₅ to C₂₁aliphatic hydrocarbon group.
 7. The composition according to claim 1,wherein component b) additionally comprises an additional oxygenscavenger selected from the group consisting of sodium sulfite,hydrazine, diethylhydroxylamine (DEHA), carbohydrazide, erythorbic acid,methylethylketoxime (MEKO), and hydroquinone.
 8. The compositionaccording to claim 1, wherein the composition additionally comprises atleast one other biocide selected from the group consisting ofTetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione (Dazomet);N,N′-Methylene bis(5-methyl oxazolidine) (MBMO);1,3-Bis(hydroxymethyl)-5,5-dimethylimidazoline-2,4-dione (DMDMhydantoin).
 9. The composition according to claim 1, wherein componentd) is selected from the group consisting of fluorescein, disodium salt(9-o-Carboxyphenyl-6-hydroxy-3-isoxanthone, disodium salt); C.I. 45350disodium salt; C.I. 766; C.I. Acid Yellow 73; D&C Yellow No. 8; Disodium6-hydroxy-3-oxo-9-xanthene-o-benzoate; fluorescein sodium; xanthene dyeas shown in Formula (IV);9-(2-carboxyphenol)-3,6-bis(diethylamino)-xanthium chloride (RhodaminB); C.I. 45170; Basic Violet 10 as shown in Formula (V)


10. The composition according to claim 1, wherein the compositionadditionally comprises a co-solvent selected from primary, secondary andtertiary monohydric alcohols with between 1 and 20 carbon atoms, anddiols with between 2 and 20 carbon atoms.
 11. The composition accordingto claim 1, wherein the composition additionally comprises a mutualsolvent selected from the group consisting of 2-ethyl-hexanol, ethyleneglycol ether of 2 ethyl-hexanol, polyethylene glycol ethers of 2ethyl-hexanol and propylene glycol.
 12. The composition according toclaim 1, wherein composition additionally comprises water.
 13. Thecomposition according to claim 1, wherein 10 to 70 wt.-% of component a)are present.
 14. The composition according to claim 1, wherein 1 to 50wt.-% of component b) are present.
 15. The composition according toclaim 1, wherein 1 to 20 wt.-% of component c) are present.
 16. Thecomposition according to claim 1, wherein 1 to 20 wt.-% of component d)are present.
 17. The composition according to claim 10, wherein 1 to 30wt.-% of co-solvent are present.
 18. The composition according to claim11, wherein 1-30 wt.-% of the mutual solvent are present.
 19. Thecomposition according to claim 12, wherein water is present ad 100wt.-%.
 20. The composition according to claim 1, wherein 1 to 25 wt.-%of other compounds selected from the group consisting ofpolyglycolethers and inorganic salts are present.
 21. A process forpressure testing oilfield equipment using an aqueous pressure medium,the process comprising adding to the aqueous pressure medium acomposition, comprising a) at least one quaternary ammonium compound ofthe formula (I)

wherein R is a C₅ to C₂₁ aliphatic hydrocarbon group, X is an anioniccounter ion, and R^(a), R^(b) are selected from the group consisting ofhydrogen, methyl, ethyl, allyl, propyl, butyl, phenyl or benzylresidues, b) ammonium bisulfite, sodium bisulfite, or both c)glutaraldehyde, THPS, or both, and d) at least one organic dye. 22.(canceled)
 23. The process according to claim 21, wherein thecomposition is present in an amount of 100 to 2,000 mg/L of the aqueouspressure medium.